This invention relates to a method of generating active oxygen in a gas phase and more particularly to a method of generating active oxygen in an oxygen-containing gas phase by using an agent containing polyaniline.
New sterilization and deodorizing methods by using active oxygen are coming to be known because they do not require any equipment of a particular type and are highly effective. Known methods of generating active oxygen include the use of a photocatalyst such as titanium oxide and irradiation of ozone by a beam of ultraviolet light. These prior art methods of generation, however, have a basic disadvantage that they require light.
It is therefore an object of this invention, in view of the above, to provide a new method of easily generating a sufficiently large amount of active oxygen for sterilization and decomposition of organic compositions in a gas phase environment even where there is no available light.
An agent to be used in a method embodying this invention, with which the above and other objects can be accomplished, may be characterized as containing polyaniline and wherein active oxygen is generated by reacting this polyaniline with the oxygen contained in the gas phase.
According to a preferable method of using such an agent, active oxygen is generated by increasing the amount of water adsorbed to polyaniline so as to activate the oxygen in the gas phase. As water is adsorbed, polyaniline may be believed to supply electrons to the oxygen in the gas phase and active oxygen is generated such that the oxidized structures are increased in the polyaniline. Thus, it is preferable to reduce the polyaniline after active oxygen has been generated such that its ability to generate active oxygen can be restored again. In other words, as polyaniline gives off electrons to oxygen to generate active oxygen, its oxidized structures increase but if its reduced structures increase, its ability to give off electrons to the oxygen in the gas phase can be restored. According to preferred method of the present invention, polyaniline is repeatedly oxidized and reduced such that active oxygen can be generated repeatedly.
A preferable method according to this invention includes the step of reducing the amount of water adsorbed to the polyaniline after active oxygen is generated so as to restore the ability of the polyaniline to provide oxygen in the gas phase with electrons. In summary, polyaniline to be used according to this invention can generate active oxygen repeatedly by increasing and decreasing the amount of water adsorbed thereto. It may be because the reduced structures in polyaniline are increased again as the amount of adsorbed water is reduced.
Throughout herein, xe2x80x9cactive oxygenxe2x80x9d will mean all kinds of oxygen that are far more active than ordinary oxygen and can more easily start a chemical reaction, including singlet oxygen, superoxide anion radical (.O2xe2x88x92) hydroxy radical (.OH), perhydroxy radical (.OOH) and hydrogen peroxide (H2O2).
A device embodying this invention for generating active oxygen is characterized as using an agent as described above and preferably also as comprising means for reducing this agent and for causing an oxygen-containing gas to come into contact with this agent. Conventionally known chemical or electrochemical means may be used as the means for reducing the agent. In other words, a reducing agent may be used or an electric current for this purpose may be passed to increase the reducing structures in polyaniline such that it becomes possible to generate active oxygen again. The amount of water contained by polyaniline may be increased and decreased by alternately passing air with different water contents so as to intermittently cause active oxygen to be generated.
In addition to or instead of a reducing means as described above, the device according to this invention may comprise means for heating and cooling or for continuously heating the agent of this invention. If the agent is heated and cooled repeatedly or is continuously heated, the amount of water adsorbed thereto can be increased and decreased accordingly such that active oxygen can be generated intermittently. The invention does not impose any particular limitations on the kind of such means for heating and cooling or continuously heating the polyaniline. A heater or a cooler of a usual kind such as a Peltier element may be utilized. Neither does the invention impose any particular requirement on the kind of the means for contacting an oxygen-containing gas to polyaniline. A simple fan may be made use of for this purpose. Such a device may be used singly or may be incorporated in another device such as an air cleaner, a humidifier, an air conditioner, a deodorizer or a device for decomposing small amounts of organic substances.